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排序方式: 共有1448条查询结果,搜索用时 31 毫秒
31.
福建果树根部的芒果半轮线虫记述   总被引:4,自引:2,他引:4  
 芒果半轮线虫(Hemicriconemoides mangiferae Siddiqi,1961)在福建省一些果园发生。寄主有龙眼(Euphoria longana)、荔枝(Litchi chinensis)、芒果(Mangifera indica)、橄榄(Canarium album)、枇杷(Eriobotrya japonica)和葡萄(Vitis vinifera)等果树。雌虫唇部正面、环纹和阴门,雄虫侧带以及幼虫角质膜刺突等细微结构用扫描电子显微镜观察。  相似文献   
32.
During the summer 1996, twelve of twenty-eight leek plants located in a garden near eské Budjovice, South Bohemia exhibited symptoms typical of diseases associated with phytoplasmas. In summer 1998 similar symptoms were detected in leek plants in a field used for seed production located in Romagna, North Italy. In both cases the plants were established in the spring of the previous year. Plants showed flower abnormalities: stamen elongation, anther sterility, pistil proliferation, as well as poor, if any, seed production. Phytoplasma-like structures were detected by scanning and transmission electron microscopy in phloem sieve elements in the Czech diseased plants, but not in healthy ones. Nested-PCR amplifications of extracted DNA with phytoplasma-specific oligonucleotide primer pairs confirmed the presence of phytoplasmas in these plants at low concentrations. Restriction fragment length polymorphism analyses of amplified ribosomal sequences allowed the identification of detected phytoplasmas: all the samples from the Czech Republic contained aster yellows related phytoplasmas (16SrI-B) while in the Italian samples aster yellows related phytoplasmas (16SrI-B) together with stolbur related phytoplasmas (16SrXII-A) were identified. This is the first report of detection and identification of a phytoplasma disease of leek in the Czech Republic and Italy.  相似文献   
33.
家鸡蛋壳组织结构的扫描电镜观察   总被引:4,自引:1,他引:3  
用扫描电子显微技术对家鸡蛋壳结构进行研究的结果,进一步直观形象地丰富了我们在这个领域的知识。  相似文献   
34.
A retrospective study was performed on skin samples from an outbreak of cutaneous papillomatosis in Merino sheep that occurred in 1995. The samples were processed for routine histology, electron microscopy and immunocytochemistry for papilloma viruses. Particles of approximately 55 nm diameter were found in some nuclei of the stratum granulosum cells, while immunocytochemistry gave positive staining of cell nuclei in this layer. This study confirms that papillomas associated with papillomaviruses occur in sheep in Patagonia.  相似文献   
35.
The discovery of the spiral bacterium Helicobacter pylori and its causative role in gastric disease in humans has brought a dramatic change to gastroenterology. Although spiral bacteria have been known for more than a century to infect the stomachs of dogs and cats, recent research has been conducted mainly in the wake of interest in H. pylori. H. pylori has not been found in dogs and only very rarely in cats and zoonotic risk is minimal. A variety of other Helicobacter spp. can infect the stomach of pets; however, their pathogenic role is far from clear, and they have a small but real zoonotic potential. The prevalence of gastric Helicobacter spp. in dogs and cats is high, irrespective of clinical signs, and as in human medicine, mode of transmission is unclear. The relationship of Helicobacter spp. to gastric inflammation in cats and dogs is unresolved, with inflammation, glandular degeneration, and lymphoid follicle hyperplasia accompanying infection in some but not all subjects. Circulating anti-Helicobacter immunoglobulin G antibodies have been detected in 80% of dogs with naturally acquired infection and most dogs and cats with experimental infection. The gastric secretory axis is similar in infected and uninfected cats and dogs and no relationship of infection to gastrointestinal ulcers has been found. Differences in the pathogenicity of Helicobacter spp. are apparent, because infection with H pylori is associated with a more severe gastritis than infection with other Helicobacter spp. in both cats and dogs. Rapid urease test, histopathology, and touch cytology are all highly accurate invasive diagnostic tests for gastric Helicobacter-like organisms in dogs and cats, whereas culture and polymerase chain reaction are the only means to identify them to the species level. Urea breath and blood tests or serology can be used to diagnose Helicobacter spp. noninvasively in dogs and cats. Most therapeutic studies in pets have not shown long-term eradication of Helicobacter spp. Whether this is due to reinfection or recrudescence has not been established.  相似文献   
36.
AIM:To investigate the functional changes and histopathological basis of Oddi’s sphincter under hypercholesterolemia. METHODS:Twenty - four New Zealand rabbits were equally divided into be groups ran- domly. Experimental groups Ⅰ and Ⅱ fed with cholesterol - added forage for 4 and 8 weeks respectively before sacri- ficed. Images, functions and histopathological characteristics of Oddi’s sphincters of experimental groups were studied and compared with control group by cholangiography, catheter manometry, and quantitative analysis of nitric oxide synthase. RESULTS: The hasal pressures of proximal low - pressure segment of Oddi’s sphincter of hath experimen- tal groups Ⅰand Ⅱ (20.9±6.1 mmHg, 25 .6±9.1 mmHg, respectively) were higher than those of control group sig- nificantly (11.7±2.8 mmHg, P < 0.01, P < 0.01 ). The hasal pressures of distal high - pressure "valve" segment of both experimental pops (138 .4±45. 5 mmHg and 144. 5 ±40 .4 mmHg, respectively) were significantly higher than those of coned group (69.3±9.8 mmHg, P < 0.01 and P<0.01). The gallbladder volUmes of experimental group Ⅰ and Ⅱ (3.4±1.0 mL and 3.9±1.9 mL) were significantly larger than those of control group (2.0 ±1.9 mL, P < 0.05 and P < 0.01 ). Between groups there were no significant differences in nitric oxide synthase con- tents. Enlargement of the cell volume, wavy distortion of the cell membrane, loosening and disarrangement of myofila- ment, uneven in size and distribution of dense body, angulation of longitudinal axis between dense body and myofila- ment, swelling, congregated at one end of nucleoulus and disappearance of cristae of plasmosomes and concertration of chromosome at nucleolus margin were observed in experimental groups under electron-microscope. CONCLUSION: The diastole function of Oddi’s sphincter could be damaged by hyperecholesterolemia, inducing a functional disorder of Oddi’s sphincter with increased resistance in bile excretion. The result is retertion of bile in the gallbladder.  相似文献   
37.
We investigated the physicochemical properties of the thermal gel of water‐washed pork meat (WWM) in the presence of the soluble fraction of porcine sarcoplasmic protein (SP) obtained with ammonium sulfate at 75 percent saturation. Two precipitated fractions of SP were obtained at 0–50 percent and 50–75 percent saturation, named SP‐f1 and SP‐f2, respectively, and the soluble fraction obtained at 75 percent saturation, SP‐f3, was used. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that SP‐f3 contained mainly glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), while SP‐f1 and SP‐f2 had other SPs such as phosphorylase b, enolase, actin and phosphoglycerate mutase. The gel strength of WWM was greater when SP‐f3 rather than one of various animal proteins such as bovine plasma (BP), egg white, or whey protein isolates (WPI), was added and SP‐f3 had a gel‐enhancing effect as good as that of polyphosphate (PP). The gel strength of WWM with added SP‐f3 increased significantly with NaCl at 0.15 mol/L or more, but not in the absence of NaCl (0 mol/L). The effect of SP‐f3 was evident at neutral pH and maximum gel strength was obtained at a pH above 6.0. Differential scanning calorimetric (DSC) analysis showed that an endothermic peak corresponding to myosin heads in WWM shifted to a lower temperature with the addition of SP‐f3, as in the case of PP, though there was no such shift in the presence of other animal proteins (BP, egg white and WPI), suggesting that SP‐f3 increases the gel strength of WWM through the dissociation of actomyosin similar to PP. Scanning electron microscopy (SEM) revealed wall‐like structures among the protein strands in the WWM gel matrix in the presence of SP‐f3. The results of DSC and SEM indicated that the formation of a gel network in meat products is reinforced with GAPDH in SP after the interaction between GAPDH and myofibrillar protein.  相似文献   
38.
棉铃虫齿唇姬蜂触角感器的扫描电镜观察   总被引:7,自引:2,他引:7  
棉铃虫齿唇姬蜂雌雄蜂触角上感器的扫描电镜观察结果显示,共发现毛形感器、板形感器、钟形感器、锥形感器、Bohm氏鬃毛和刺形感器6类感器,分别对这6类感器的类型与形态进行了详细描述,并对各种感器的功能进行了深入的分析和讨论。  相似文献   
39.
Fungal colonisation of winter wheat cv. Cadenza by Fusarium culmorum, F. graminearum and Microdochium nivale was studied under conditions designed to avoid the splash dispersal of conidia from infested compost, to evaluate the possibility that systemic growth may transfer infection from the stem-base to the head. At decimal growth stages 33, 59, 77–87 and 95 the extent of fungal growth was assessed using a sample of 72 plants, by the recovery of fungal species from the stem-base, from each node and from the ear. Each of the fungi was recovered from stem tissues above soil level in some, apparently symptomless, plants. Symptoms of Fusarium foot rot were seen in an increasing proportion of plants during grain-fill and desiccation. There was an inverse relationship between recovery and the height above stem-base from which the stem tissue was excised. F. culmorum was the most frequently isolated fungus and it was also recovered from the highest position in plants. Only 3% of plants were colonised above the second node and none of the fungal species were recovered from either the fifth node or the ear. This suggests that colonisation and systemic growth from Fusarium infested compost is unlikely to contribute to the development of ear blight symptoms in winter wheat.  相似文献   
40.
电子文件的大量出现,不仅对档案管理理论造成了很大的冲击,更重要的在于促使管理理念的更新,管理视角的转变。通过对近年的电子文件定义及其特点综述、电子文件对档案业务管理工作的影响、及电子文件档案学理论的影响和对策进行简要介绍。  相似文献   
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